Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KGSP 091132
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
732 AM EDT WED JUL 9 2014

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY IN
THE MOIST AIR MASS AHEAD OF A COLD FRONT ENTERING THE REGION. THAT
FRONT WILL STALL OVER THE AREA TONIGHT AND ENHANCE PRECIPITATION
CHANCES THURSDAY BEFORE WEAKENING FRIDAY. WEAK HIGH PRESSURE WILL
RETURN THROUGH THE WEEKEND BEFORE ANOTHER COLD FRONT APPROACHES THE
AREA EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
S OF 7 AM...STILL WATCHING SPOTTY SHOWERS LIFTING NORTHEAST ACROSS
THE GREAT VALLEY...BASICALLY SKIRTING THE WESTERN NC MTNS. POPS HAVE
BEEN SCALED BACK A BIT MORE FOR THIS MORNING...BUT WILL REMAIN IN
THE CHANCE RANGE ACROSS THE MTNS.

PREVIOUS DISCUSSION:
THERE IS VERY LITTLE ONGOING CONVECTIVE ACTIVITY IN OR IMMEDIATELY
UPSTREAM OF THE CWA...NOT SURPRISING CONSIDERING THAT THE AREA IS
WITHIN AN INSTABILITY MINIMUM. NEVERTHELESS...THERE IS STILL SOME
WEAK BUOYANCY UPSTREAM OVER THE TENN VALLEY...AND LATEST KGSP VAD
WIND PROFILE IS CONFIRMING A STOUT 25 TO 35 KTS OF WESTERLY FLOW
ABOVE ABOUT 2 KFT. IN ADDITION...SCATTERED SHOWERS WERE DEVELOPING
AT 07Z ALONG THE WINDWARD SIDE OF THE CUMBERLAND PLATEAU...WHICH
WOULD PROBABLY ARRIVE IN THE FAR WESTERN NC MTNS BY THE START OF THE
PERIOD. WE WILL CONTINUE TO RAMP POPS UP TO HIGH CHANCE ACROSS THE
TENN BORDER COUNTIES BY SUNRISE.

OTHERWISE...THE CONVECTIVE SETUP FOR LATER TODAY LEAVES MUCH TO BE
DESIRED. THE FRONTAL ZONE...SUCH AS IT IS...IS STILL DRAPED FROM THE
OHIO VALLEY W/SW TOWARD THE ARKLATEX. IN OTHER WORDS...IT HAS A LONG
WAY TO GO TO BE A PLAYER IN CONVECTIVE CHANCES ACROSS OUR AREA THIS
AFTERNOON. IN FACT...IT MAY TURN OUT THAT THE MAIN FOCUS (OTHER THAN
THE USUAL TERRAIN/DIFFERENTIAL HEATING EFFECTS) MAY BE A LEE SIDE
TROUGH...BUT EVEN THAT MAY BE MORE OF A CONCERN FOR AREAS JUST TO
OUR EAST. ADDITIONALLY...THERE IS A FAIRLY STRONG SIGNAL IN THE
LATEST MODEL GUIDANCE...AND IN OBSERVATIONAL TRENDS...THAT PESKY
MID/HIGH LEVEL CLOUDS WILL HINDER DIURNAL DESTABILIZATION. IN
FACT...FOR THIS VERY REASON THE MAX TEMP FORECAST IS 2-4 DEGREES
LOWER THAN WHAT WE HAVE SEEN THE PAST COUPLE OF DAYS. FINALLY...
WHILE PROFILES WILL BE MOISTENING CONSIDERABLY...FORECAST PWATS ARE
ONLY 1-2 STANDARD DEVIATIONS ABOVE CLIMO. ALL THINGS CONSIDERED...
HAVE ESSENTIALLY OPTED FOR A SHOTGUNNED 40-50 POPS ACROSS THE CWA...
WITH A SMALL AREA OF LIKELY ACROSS THE SOUTHWEST MTNS...WHICH WILL
HAVE THE BENEFIT OF A CONTINUED (ALBEIT WEAKENING) W/SW UPSLOPE
FLOW. IN TERMS OF THE SEVERE THREAT...MODEST INSTABILITY/MOIST
PROFILES AND WEAKENING SHEAR SHOULD LIMIT THE POTENTIAL
CONSIDERABLY. HOWEVER...THE PIEDMONT WILL HAVE TO BE WATCHED
CLOSELY...ESPECIALLY IF INSOLATION/HEATING IS MORE SIGNIFICANT THAN
EXPECTED.

THE FRONTAL ZONE WILL FINALLY SETTLE INTO THE AREA TONIGHT...BUT BY
THAT TIME...WITH WIND PROFILES WEAKENING AND MODEST AT BEST
NOCTURNAL INSTABILITY...SUSPECT IT WILL BE DIFFICULT TO GET MUCH
MORE THAN SCATTERED CONVECTION FOR TOO LONG PAST MID-EVENING OR SO.
MIN TEMPS WILL REMAIN ABOVE CLIMO UNDER CONSIDERABLE CLOUD
COVER.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 200 AM WED...SFC FRONT WILL SLOWLY MOVE SEWD THRU THE DEEP
SOUTH AND THE CAROLINAS FROM THURSDAY INTO EARLY SATURDAY...WHILE
BROAD HIGH PRESSURE BUILDS TOWARD THE EAST COAST AS HEIGHTS RISE
ALOFT. DEEP THICKNESSES DO NOT DROP APPRECIABLY BEHIND THE
FRONT...AND IN SOMEWHAT OF A DEPARTURE FROM PREVIOUS RUNS...LATEST
MODEL SOLUTIONS APPEAR TO WEAKEN THE FRONT AND VIRTUALLY WASH IT OUT
OVER THE PIEDMONT INSTEAD OF PUSHING IT OFF TO THE COAST AS BEFORE.
HOWEVER THIS DIFFERENCE DOES NOT IMPLY MAJOR CHANGES TO THE FCST
TRENDS SINCE THE FRONT SHOULD MAINLY JUST SERVE TO FOCUS DIURNAL
CONVECTION ACRS THE AREA. WILL CONTINUE TO ADVERTISE HIGH CHANCE POPS
THU...BUT WILL KEEP A SCHC OVER MOST AREAS THRU THU NIGHT. WHATEVER
WEAK LLVL FORCING PERSISTS LOOKS UNLIKELY TO FIRE MUCH
CONVECTION...BUT THE MERE PRESENCE OF THE BOUNDARY AND MODEST LAPSE
RATES WARRANT A LOW POP MENTION. BY FRIDAY MODEL QPF RESPONSE FAVORS
THE SC MIDLANDS AND CENTRAL NC. MOSTLY SCHC POPS ARE ADVERTISED...BUT
THESE TOO ARE SLOW TO DIMINISH FRI NIGHT.

CONSENSUS OF NAM/SREF INDICATES CAPE VALUES EACH AFTERNOON WILL BE
TYPICAL FOR THE SEASON...1000-2000 J/KG...THOUGH THE GFS IS MORE
STABLE FRIDAY WITH MORE OF THE REGION ON THE COOL SIDE OF THE FRONT.
H5 WINDS AND SHEAR PROFILES ARE UNIMPRESSIVE...AND PWAT VALUES REMAIN
NEAR CLIMO. SEVERE THREAT WITH CELLS WILL BE NONZERO BUT NOT
PARTICULARLY NOTABLE...THOUGH LOCALLY HEAVY RAIN IS LIKELY THURSDAY
BEFORE DRIER AIR MOVES IN ALOFT. TEMPS WILL REMAIN JUST BELOW NORMAL.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM TUE...WHILE SOME VESTIGE OF A FRONTAL BOUNDARY MAY
REMAIN OVER THE COASTAL PLAIN THIS WEEKEND...THE PATTERN ACRS THE
REGION WILL BE DOMINATED BY BERMUDA HIGH AT THE SFC. THAT WILL
MAINTAIN LIGHT SOUTHERLY FLOW INTO THE FA...BUT INSTEAD OF KEEPING
US CAPPED THRU SUBSIDENCE...BROADLY CYCLONIC UPPER FLOW ABOVE IT
WILL KEEP CONDITIONS MODESTLY FAVORABLE FOR DIURNAL CONVECTION. THIS
IS THE PREVAILING SIGNAL FOR POPS DURING THE PERIOD. TEMPS WILL
TREND FROM SLIGHTLY BELOW NORMAL SATURDAY TO SLIGHTLY ABOVE NORMAL
BY TUESDAY.

A FRONT WILL DIVE THRU THE NRN PLAINS OVER THE WEEKEND AS TROUGH DIGS
ACRS ERN CANADA. A WEAK LEADING FRONT WILL PUSH THRU THE OH/TN
VALLEYS AND INTO THE AREA MONDAY...ENHANCING PRECIP COVERAGE. THE
TROUGH AMPLIFIES FURTHER IN THE MIDDLE OF THE WEEK WHICH BRINGS THE
STRONGER FRONT SWD TOWARD US.  CURRENT GUIDANCE PUTS THIS ON WED
BEYOND THE END OF THE FCST.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE (EXCEPT KAVL)...CANNOT RULE OUT A FEW SHOWERS
POPPING UP OR MOVING OUT OF THE MTNS AT JUST ABOUT ANYTIME THIS
MORNING...BUT COVERAGE SHOULD BE VERY SPARSE UNTIL AFTERNOON.
OTHERWISE...PREVAILING VFR CONDITIONS ARE EXPECTED (OUTSIDE OF
SHOWERS/TSTORMS) THROUGH THE PERIOD. COVERAGE OF CONVECTION IS
EXPECTED TO INCREASE THIS AFTERNOON...BUT THERE IS STILL SOME
UNCERTAINTY AS TO THE DEGREE OR COVERAGE. OUR BEST EDUCATED GUESS
CONTINUES TO INDICATE COVERAGE SHOULD REMAIN SCATTERED...AND ALL
TAFS SEE A PROB30 DURING THE AFTERNOON THROUGH MID EVENING OR SO.

AT KAVL...OTHER THAN PERHAPS A STRAY SHOWER OR TWO DEVELOPING NEAR
THE TENN BORDER AND PASSING NEAR THE TERMINAL THIS MORNING...THE
BULK OF CONVECTIVE ACTIVITY SHOULD HOLD OFF UNTIL AFTERNOON...WHEN A
TEMPO IS BEING CARRIED BETWEEN 18Z AND 22Z...ALTHOUGH CONVECTIVE
CHANCES WILL CONTINUE INTO THE EVENING. WE ARE STILL WAITING FOR A
FOGGY NIGHT TO OCCUR AT KAVL...AND WHILE IT IS UNCLEAR THAT TONIGHT
WILL BE THE NIGHT...BASED UPON A CONSENSUS OF GUIDANCE...MVFR VISBY
HAS BEEN INTRODUCED TOWARD DAYBREAK.

OUTLOOK...SCATTERED MAINLY AFTN THUNDERSTORMS WILL CONTINUE THROUGH
LATE WEEK INTO THE WEEKEND AS HIGH PRESSURE SLOWLY SETTLES OVER THE
AREA. ANY RESTRICTIONS WOULD BE CONFINED TO DIURNAL TSTMS AND
MORNING VALLEY FOG EACH DAY.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-11Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  94%     HIGH 100%     HIGH 100%     HIGH  80%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  87%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...WIMBERLEY
NEAR TERM...JDL
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...JDL





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.